Biodegradable waste is the type of waste that can be broken down by way of composting (aerobic decomposition and anaerobic decomposition) into base compounds (H2O, CO2, compounds of Nitrogen, Phosphorus, Potassium and others), energy (heat) and residual humus. The residual humus can eventually break down into fine particles and can be automatically transported by water circulation.
Both the aerobic decomposition and the anaerobic decomposition belong to the biological process of cellular respiration, also called the slow burning. Microorganisms such as bacteria, fungi and protozoa as well as animals such as earthworm and fly larvae are all players in the composting process by way of cellular respiration. Broadly speaking, biodegradation also includes another nature process, the burning by combustion that transforms biomasses into H2O, CO2, light energy, heat energy, ash and other exhaust gases. Photosynthesis is the nature process that transforms CO2, H2O and other nutrients into biomasses by use of solar energy.
Biodegradable wastes are produced in huge volume from human activities. They include solid wastes such as kitchen food waste and backyard plant waste as well as packaging waste (papers, cartons and wood pallets etc.), waste waters such as from sinks of kitchen and from sinks, showers, bathtubs as well as toilets of bathroom, and exhaust gases such as from furnace vent and stove vent. Households and IC/I (industrial, commercial and institutional) entities, etc. are all producers of the wastes.
It is a labour burden task to collect the wastes from households and IC/I entities and to transport them into municipal treatment centers. Producers of the wastes also need to spend time and labor to get them ready for collection. Greenhouse gas emission from transport of the wastes and their recycled result products is one of the inputs leading to climate change. It costs a lot of money from both private and public in building and maintaining urban sewage piping systems for transporting waste waters into municipal treatment centers. Exhaust gases from households and industries discharged directly into atmosphere without treatment increase air pollutions.
Recycling the above wastes in the municipal treatment centers by way of composting, incineration or landfill etc. can recover some part of the beneficial ingredients from the wastes treated, but also pollutes the atmosphere, soil and even groundwater. Furthermore, it also needs large lands and costs a lot in building and maintaining the treatment utilities.
A lot of efforts have been made in addressing onsite treatment of the biodegradable wastes. Composters including vermi-composters that use natural ventilation are not in a sealed vessel therefore let go heat, odors and exhaust gases into the atmosphere.
The U.S. Pat. No. 5,744,351 to Michael Bryan-Brown discloses a bioreactor for aerobically composting organic waste inside a sealed container. It integrates a mixing assembly and an aeration system so that the inside composting wastes can be well ventilated. However, this design type needs to manage the exhaust gases by way of a bio-filter and to manage the leachate liquid by use of a pump.
The patent application No. CN101823069 by Aimin Li et al discloses an auto-controlled composter with ventilation and heat components to promote the composting process inside a vessel. Again, it still needs components to filter the exhaust gases and to manage the leachate liquid.
Both the above composters are designed for the purpose to recycle the bio wastes into compost only. The bio wastes are fed by batch into the composter, after certain time the completed compost is to be discharged and transported. Pollutants to environment can be disposed from exhaust gases, leachate liquid and completed compost. Nutrients of the bio wastes and heat from the composting wastes are not fully utilized. When these composters are employed, the bio wastes inside the vessel of a batch undergo all composting stages, therefore in each stage the quantity of microorganisms reaches its highest point and then decreases or even disappears in a later stage because of changed conditions. When the complete compost of a batch is discharged, the microorganisms inside the composter are also discharged. It is a totally new process for microorganisms to grow into large quantities during the new composting stages of the newly fed batch of bio wastes.
It is desirable that the biodegradable wastes be composted onsite within its source location with the completed compost locally used with zero mile of transportation, with zero pollution to the environment from the composting process, and with all the nutrients and heat energy from the wastes fully recovered and reused. It is also desirable that the condition of microorganisms stay unchanged when the biodegradable wastes undergo each of the composting stages.
In response to the growth of demand for healthy foods available in minimum mileage, the hydroponic technology and the aquaponic technology have been in practice for decades. When these practices happen in the household backyard or in the food consume premises, zero food mileage can be achieved as regard to the foods produced and consumed in the same location.
However, the conventional hydroponic system needs to add artificial nutrients into its circulating water to feed plants. In a typical aquaponic system fish feed is from outside source, and the waste water from integrated fishing tanks doesn't have enough nutrients to support the growing plants, therefore minerals and other nutrients have to be added. Furthermore, a filter and a bioreactor are required to separate and to degrade solid wastes in the waste water from the aquaponic fish tanks.
Compost tea is one of the options to supply nutrients to plants in the hydroponic and aquaponic systems. Compost tea is produced by putting a bag of compost into a vessel with aerated water for certain time to allow microbes grow. It is nutritious for growing plants and therefore good to be added into the hydroponic and aquaponic systems. Different devices are available but are separately operated from the hydroponic and aquaponic systems.
Although it is valuable to grow short mileage foods with little water loss by way of the hydroponic system or the aquaponic system, their values are limited by the high start-up costs comparing to the volume of foods produced, for they are used to grow foods only. The system does not automatically recycle waste biomass produced from itself and from other sources. Another concern is quality of the soilless cultured foods. Some food plants don't fit for soilless culture, while quality of soilless cultured foods may be different from soil cultured foods.
It is desirable to have a bioreactor system that can be integrated into the hydroponic system or the aquaponic system, which can onsite automatically recycle biodegradable wastes into nutrient liquid to feed the growing plants, and that can also grow feed for the aquarium animals. Furthermore, it is desirable to have a bioreactor system that can be integrated into the food growing systems, that can automatically recycle all the biodegradable wastes including solid wastes, waste waters and exhaust gases from both the food production sources and from the onsite human activities, and that can fully recover nutrients and heat energy from the treated wastes to grow foods with zero pollution to the environment. It is also desirable that soil growing beds may be integrated into the food growing system so that most kinds of food plants can be cultured in an integrated system.
The patent application No. CA2759981A1 by Nicholas Hermes and James Sawada discloses a food production system that composts biomass and uses the completed compost to grow foods with heat and nutrients recovery. In this system biomasses are fed by batch mode to a composter and then physically transferred into another invertebrate culture unit and lastly transferred into a food culture unit. The heat recovery is carried by way of a complicated pipe system which circulates heat exchange liquid. In this design, the biomass is not kept inside of a sealed vessel during all processes; pollutants to environment can be disposed from the exhaust gases while nutrients and heat are not fully recovered.
In the prior art composters that can be employed onsite of the waste source, the biomasses or the bio wastes or the organic wastes or the biodegradable wastes that can be fed into the composter, have numerous limitations. The wastes such as wood pallets, tree trunks and branches of large size are usually not acceptable. The present invention provides an onsite biomass composting and reuse, which overcomes the limitations of the prior art.
One of the important steps for sealed in-vessel composting is to mix or agitate the inside contents so that all the volume is well aerated. Either a slow speed motor that rotates the whole vessel/drum or a fast speed motor that drives an agitator to cause movements of the whole volume is usually employed. In the U.S. Pat. No. 5,744,351, a vertically installed slidable mixing assembly is employed so that almost all the inside volume can be reached for agitation. This method requires a worker to manually operate the mixing assembly. In the patent application CN101823069, a mixing module is horizontally installed and it horizontally rotates the whole volume inside the vessel. All these methods are not efficient in comparing the power energy required with the simple aeration resulted.
The traditional plow, especially the chisel plow is typically much more efficient in comparing the power required with the volume of mass (soil) moved or agitated. Inside a sealed vessel, if some part of the contents along the bottom layer is physically moved, it can cause somewhat movements of the whole contents. This kind of movements are good enough for aeration of the whole volume, especially if the air is from a space below the volume. Desirably a very slow speed movement caused by rotating a chisel plow type agitator can well aerate the whole volume.
Also, most prior art agitators for in-vessel liquid agitation are designed for high speed rotation movements that cause movements of the whole volume. During very slow rotation, the volume and the dimensional range moved by these agitators are very limited therefore can not reach good agitation effects. It is desirable to have a specially designed liquid agitator that can reach better agitation effects from slow speed rotation, especially for the concaved or conical volume in which the height gradually decreases from the middle point to the side wall point.
One of the methods to heat greenhouse is to use a rocket stove by burying its chimney tube in ground to hold heat from the circulating combustion flue gas. This is a right way to “degrade” by burning large branches and tree trunks which cannot be acceptable to the onsite composters. But this method causes exhaust gas emission because the combustion flue gas goes directly into the atmosphere.
Studies have proved that plant growth can be stimulated by elevation of CO2 ppm [HortScience Vol 46(2):158-162 February 2011]. This method has been practiced in greenhouse farming. Studies have also proved that high concentration (up to 10,000 ppm) of CO2 can kill pests inside a closed space, therefore CO2 has been used as fumigant for stored grain utility (Nathan J Dyrud: University of Minnesota Extension Service (2001), Private stored grain fumigation manual 3-3).
In recycling the bio-degradable wastes into good staff for growing uses, the prior arts tend to deal the processes separately therefore don't solve the problem in high efficiency and even cause problems to each other. The apparatuses designed to treat solid wastes take the leachate liquid and exhaust gases as extra burdens which have to be specially managed. The apparatuses designed to treat waste waters take the solids inside as extra burdens which have to be specially managed. The apparatuses designed to treat exhaust gases have to employ liquid and solid filter media. The apparatuses designed to produce compost tea have to create conditions to grow microorganisms from the completed compost in which most of the microorganisms are not in the best state of activity and quantity. The apparatuses designed for vermi-composting have to manage the humidity of the fed solid waste, and the fed waste has to undergo a first stage of composting before it becomes food for worms. In winter, we need to buy fire woods or gas to heat a greenhouse while we put a lot of staff that is good for heating by burning into garbage bins that causes a lot afterward works to have it treated somewhere far away.
In the patent application US 2007/0059819A1, Stephen Storch discloses an apparatus for brewing compost tea composing of a plurality airlift pumps for agitation and aeration. This design causes a swirling vortex in the tank. Most of the nowadays apparatuses used for brewing compost tea have employed this technique, however, in all the apparatuses the swirling vortex is created for agitation and aeration only, the kinetic energy of the swirling vortex is not harnessed for good use.
It is desirable to have a system that integrates together all the functions of the above mentioned prior art apparatuses in which every burden becomes a good input into a circulating process. It is further desirable that the kinetic energy from the swirling vortex can be harnessed for good uses in an integrated system such as mixing and agitating solid wastes. It is also desirable to have a specially designed turbine that can harness the kinetic energy from the swirling vortex in high efficiency.